The use of high-frequency alternating currents (for example in the frequency range of between 300 KHz and 2 MHz) to produce high temperatures for tissue coagulation and for tissue division has already long been known in surgery. In practice so-called monopolar electrode arrangements or bipolar electrode arrangements are used to introduce the HF-current into the tissue.
In the monopolar arrangements an electrode—also referred to as the neutral electrode—is in the form of a large-area electrode which is applied in the proximity of the treatment location to the skin of the patient and fixed there and grounded, or connected to ground. A second electrode which is handled by the operator—also referred to as the active electrode—is connected to the ac voltage source. The electrode is adapted in respect of its shape to the respective use, in particular to the size of the tissue region to be treated, in such a way that both the operating time and also the thermal loading of the body region or organ in question are reasonable and only coagulate the desired region of tissue.
In arrangements for bipolar HF-thermotherapy both electrodes are connected to a HF-generator and are of dimensions which are established in conjunction with each other, arranged for example on an insulating elongate carrier, and are placed by the operator in the immediate proximity of the parts being treated and are generally also actively guided.
PCT application WO 97/17009 discloses a bipolar electrode arrangement with a flushing passage by way of which flushing fluid can be introduced into the intervention region. Two or three electrodes are arranged in the form of a portion of a cone on a conical distal tip of the instrument, which can be inserted into the tissue, in which case the electromagnetic HF-field is formed between the electrodes and is intended to coagulate the surrounding tissue.
PCT application WO 96/34569 and the publications referred to in the related international search report disclose systems and processes for the coagulation of body tissue and observing a pre-calculated maximum tissue temperature, in which fluid cooling or thermoelectric cooling is provided during the actual tissue coagulation procedure. Those known arrangements are intended for introduction into body cavities by way of natural accesses.
PCT application WO 00/36985 which was published after the relevant date discloses an electrode arrangement of that kind, in which two bar profile members are in the form of solid profile members and between them a spacer element which preferably comprises optical waveguides. Integration of the optical waveguides between the two bar profile members is however complicated and expensive. In addition the supply of fluids, in particular flushing fluids or cooling fluids, and/or sucking away body fluids which occur at the treatment location, is complicated and expensive.